If you've noticed changes in your body recently, it's likely you're just experiencing the natural progression of aging. Your body at 30 isn't going to look like your body at 20, and so on—and it's not supposed to! Your cells and organs are constantly evolving, and whatever is happening on the inside will often affect how we look on the outside.
When it comes to physical changes, people often wonder if their metabolism is playing a part in their body composition—especially as they age. So, we asked experts in the space to break down when metabolism slows down, what causes the metabolism to slow down, and what you can do to help it stay active.
What is metabolism?
Registered dietitian and certified intuitive eating counselor Courtney Vickery, M.S., R.D., L.D., defines metabolism as the processes that occur in the body to create the energy used to help our body "perform even the most basic functions." Everything from breathing to maintaining homeostasis with our body temperature circles back to a healthy metabolism, and it starts, Vickery says, with the food you eat.
There are three types of metabolism: catabolism, anabolism, and metabolism at rest. Catabolism, Vickery explains, involves the breaking down of molecules to release energy (ATP) that powers various bodily functions. Conversely, anabolism is the building up of molecules with the same energy released through catabolism in order to grow and repair bodily tissue.
Metabolism at rest "refers to the energy expended by the body while it is at rest—such as breathing and maintaining body temperature," Vickery says. The rate at which your body burns calories at rest is called your basal metabolic rate (BMR) and requires a minimum amount of calories to perform properly.
"When the general population hears 'metabolism,' they are typically thinking of the three different ways we expend energy: basal metabolic rate (BMR), thermic effect of food (aka TEF—the energy required to digest, absorb, and metabolize food), and physical activity (the energy used, or calories burned, during physical activity and exercise)," Vickery explains. These are the three main components that affect a person's metabolism—i.e., the ability to use energy most optimally in the body.
When does your metabolism slow down?
Vickery tells mindbodygreen that while it was originally believed that a person's metabolism would begin slowing down at the age of 30 (in increments of 2% to 5% per decade), "recent studies have shown this may not be the case."
According to a 2021 Science review, metabolism stays pretty consistent1 throughout your life: The findings suggest that, initially, the metabolism of a newborn is akin to that of an adult but increases in the first year of life. From there, metabolism is thought to "gradually decline" until age 20 and maintain its speed through age 60.
But again, your metabolism doesn't plummet when the clock strikes midnight on your 60th birthday. After 60, the total energy expenditure and BMR of the study's participants only declined by 0.7% per year, which suggests that metabolism doesn't drastically slow down with age.
Generally speaking, there's no definitive age at which every human body's metabolism will start to slow down, nor does it happen dramatically. That said, a person's metabolism can significantly slow down as a result of hormonal or energetic fluctuations, nutrient deficiency, loss of muscle mass, or a higher burden of toxin exposure.
According to Kyrin Dunston, M.D., FACOG, a board-certified OB/GYN with fellowship training in anti-aging, metabolic, and functional medicine, you should seek an assessment from a professional health care provider if you notice a drastic shift in your metabolism in your 20s or 30s "to prevent further complications down the line" and improve your metabolic health. This should also be a person's first course of action should they notice their metabolism has significantly sped up. Vickery warns metabolic health changes can be caused by an underlying culprit (e.g., thyroid issues) and can have "unwanted consequences on the body if left unaddressed."
How to know your metabolism is slowing down.
In the same way that your metabolism won't drastically dip overnight, there will also be clear signs over time that your metabolism is beginning to slow down. The key is to take note of these telltale signs now so that you're aware and able to contact your health care provider for further assessment.
Here, Vickery lists seven ways to know your metabolism is slowing down:
- You're having difficulty losing weight or maintaining a healthy weight: When metabolism slows down, we burn fewer calories, which makes it harder to lose weight or maintain a healthy weight.
- You're experiencing frequent bouts of tiredness: When metabolism slows down, it makes it harder for the body to convert food into energy. And less energy leads to feelings of tiredness.
- You're having trouble with regularity: The movement of food through our digestive system will also slow down, which can cause you to become backed up.
- You can't handle the cold: Remember that one of the functions of metabolism is to help maintain body temperature. So, when it slows down, you will see a decrease in body heat production, making you more sensitive to cold temperatures.
- Your skin feels drier than usual: A slower metabolism can also lead to fewer skin oils being produced and results in less hydrated skin.
- You've started losing your hair: Hormonal fluctuations can be related to a decreased metabolism, which can lead to hair loss.
- Changes in your menstrual cycle: Hormone fluctuations that manifest as changes in your typical cycle can be another sign of decreased metabolism.
If you experience one or more of these side effects, you should seek assistance from your health care provider, as there are tests they can run to determine if your metabolism is considered slow, fast, or just right. Some methods Vickery is most familiar with are the glucose tolerance test (GTT), which determines your body's ability to process glucose; the thyroid function test (TFT), which detects issues with the thyroid; the VO2 max test, which measures how much oxygen you use during physical activity; and body composition analyses, which estimate or measure the amount of body fat, muscle, and bone in a person's body.
Another option is something called the doubly labeled water (DLW) method (almost exclusively used in research or clinical settings), which Dunston defines as another method to measure metabolism. "Here, burned calories are measured by tracking the amount of carbon dioxide that a person exhales throughout their daily activities," Dunston tells mindbodygreen. "During the test, your blood is drawn at various intervals during exercise and the levels are compared. When your body doesn't have enough oxygen to promote the conversion of calories into energy, it switches to anaerobic respiration, which produces lactic acid or lactate. This is only done in a medical setting under specific conditions," she explains.
What to do if your metabolism is slowing down.
Incorporate different types of food into your diet.
If you tend to stick to the same meals and snacks from day to day, it's time to switch up your daily menu. According to Vickery, eating a diverse diet "will ensure that you are getting the nutrients you need in order for your body to function and perform at its best."
Clock in some quality Zzz's.
Vickery warns that a lack of sleep "can impact hormones that control appetite and metabolism, so getting enough sleep may help [speed things up]." If you're having trouble falling asleep or staying asleep through the night, it might be worth chatting with a sleep specialist to explore ways to improve your snooze.
In a 2016 review published in the journal Frontiers in Nutrition, researchers found that drinking water promotes water-induced thermogenesis2 (a process in which water has a thermic effect over the food you eat and therefore breaks down as energy) and increases metabolic rate by up to 30% for an hour in animal studies. By now, you probably know that staying hydrated helps you perform at your best, but according to these findings (and Vickery), it can also help your metabolism perform at its best.
Move your body.
According to Dunston, physical activity can help give your metabolism a boost. Weight training, she says, is especially beneficial.
"Increasing your muscle mass helps you to burn calories at a higher rate when you're sitting and doing nothing. This is because your muscles are the biggest utilizer of your caloric intake; they are hungry for energy," Dunston says. "You burn calories just sitting and breathing while doing nothing, so if you can increase your muscle mass with resistance training or weights, then you will burn more calories while sitting and doing nothing."
Add a metabolism-supporting supplement to your routine.
In addition to the aforementioned tips, targeted botanicals can also help flex your metabolism potential. By incorporating a supplement like mindbodygreen's metabolism+ into your daily routine, you can benefit from clinically researched plant bioactives.
The formula is vegetarian and free of gluten, GMOs, dairy, and soy, and void of all major food allergens. Highlighted ingredients include veld grape (which is rich in flavonoids, stilbene, and ketosterone bioactives that combat oxidative stress, promote healthy blood pressure and fasting blood sugar, and support a healthy weight) and grains of paradise (an edible spice from the ginger family that helps to burn calories by activating thermogenic brown adipose tissue3, aka BAT).* The supplement also delivers cayenne pepper, which is rich in antioxidants and helps curb cravings4, as well as antioxidant-rich EGCG and caffeine sourced from green tea leaves that encourage metabolic synergy5 when combined.*
When does your metabolism peak?
"Experts argue as to the exact age at which metabolism peaks; some say it's at one year of age, when growth is at an all-time high, and others say it's in the 20-year age range," Dunston tells mindbodygreen. "The fact is that it's highest in children and young adults for sure."
How do I know if my metabolism is slowing down?
There are signs that your metabolism is slowing down. According to Dunston, feeling tired, gaining extra weight or having difficulty losing weight, having lower sexual desire than usual, hair loss, memory or mood concerns, and gastrointestinal issues can all be presenting side effects of a suboptimal metabolism.
What are the signs of high metabolism?
When metabolism swings to the opposite extreme, "low body fat and muscle mass, difficulty gaining or keeping on weight, voracious appetite, and high energy that's difficult to calm can all be signs of high metabolism," Dunston says.
It's natural for your metabolism to fluctuate throughout your life. It's fast when you're young and gradually slows down with age—but not as rapidly as you might think. New findings suggest that your metabolism stays somewhat consistent between 20 and 60 years old (obviously, personal differences and clinical scenarios can differ!), but it can slow down significantly due to muscle losses, hormonal or energetic fluctuations, nutrient deficiency, or a higher burden of toxin exposure.
Luckily, there are ways to invigorate and reset your metabolism naturally—such as making changes to your diet, getting better sleep, and taking a targeted supplement like mindbodygreen's metabolism+.* If you feel as if your metabolism might be slowing down, talk to your health care provider for further assessment.
Julia Guerra is a health and wellness writer reporting for mindbodygreen, Elite Daily, and INSIDER. Formerly the beauty editor for BestProducts.com, she's contributed to Women's Health, Cosmopolitan, PopSugar, and more. A book worm and fitness enthusiast, her happiest moments are spent with her husband, family, sipping tea, and cuddling with her Tabby cat, Aria.